In Norse mythology, Muspelheim ("Flame land"), also called Múspell or Muspell, is a realm of fire. This realm is one of the Nine Worlds and it is home to the fire demons or the Sons of Muspell, and Surt, their ruler. It is fire; and the land to the north, Niflheim, is ice. The two mixed and created water from the melting ice in Ginnungagap.
According to the Ragnarok prophecies in Snorri Sturluson's Gylfaginning, the first part of his Prose Edda, the sons of Muspel will break the Bifrost bridge, signaling the end of times.
Muspell appears as a Dark elemental Magatama which can be obtained once the Demi-fiend defeats Mara in Shibuya Center. It focuses on inflicting mental ailments. To unlock this battle, the Demi-fiend must go to the strip mall in Shibuya at Full Kagutsuchi phase after the events at the Obelisk. The strip mall area is located behind a building in the main intersection of Shibuya. Once there, the Demi-fiend must answer "Hurry it up." to the manikins they encounter.
"A fire giant of Norse mythology. Said to live in the flaming land of Muspellheim. He stays away from the humans and the gods, but during Ragnarok, he will invade the human world."
—Devil Summoner: Raidou Kuzunoha vs. The Soulless Army devil chart
Muspell is encountered twice in the alternate reality version of Dark Ginza-Cho during Episode 9, acting as a mini-boss. He will seek to stop Raidou from progressing through the area. The second time he is encountered, he must be faced by a demon solo, as he is behind a Tainted Gate which Raidou cannot pass through.
Muspelheim is the world of Fire and Light in the Devil Children games. It is ruled by the Flame Apostle chosen by Shugoshin. The angels who inhabit it are in an endless war with the demons of Niflheim.